In order to impart various characteristics such as thermal stability, abrasion resistance, rigidity, impact resistance, and anchor effect, calcium carbonate has been added to a synthetic resin.
Patent Document 1 discloses adding calcium carbonate surface-treated with phosphoric acid to a liquid crystal polyester resin. Specifically, it discloses that using calcium carbonate that is surface-treated by a dry method of dropwise addition of orthophosphoric acid or polyphosphoric acid while stirring calcium carbonate can achieve good adhesiveness to plating and good mechanical strength.
Patent Document 2 discloses a method in which adding condensed phosphoric acid into an aqueous calcium carbonate suspension achieves surface treatment of calcium carbonate.
However, the study on calcium carbonate that is suitably contained in a polyester resin, a polyamide resin, and a thermosetting resin has been insufficient.